MFC r320165-r320166

r320165:
devd(8): Remove pidfile on shutdown

Sponsored by: Spectra Logic Corp

r320166:
Require devd to be running for its ATF tests to run

The ATF tests communicate with the system's running devd

PR: 220169
Reported by: gjb
Sponsored by: Spectra Logic Corp

MFC r289172,r290254:

r289172:

Refactor the test/ Makefiles after recent changes to bsd.test.mk (r289158) and
netbsd-tests.test.mk (r289151)

- Eliminate explicit OBJTOP/SRCTOP setting
- Convert all ad hoc NetBSD test integration over to netbsd-tests.test.mk
- Remove unnecessary TESTSDIR setting
- Use SRCTOP where possible for clarity

r290254:

Remove unused variable (SRCDIR)

MFC devd-related changes

r270004
Convert devd's client socket to type SOCK_SEQPACKET.

This change consists of two merges from projects/zfsd/head along with the
addition of an ATF test case for the new functionality.

sbin/devd/tests/Makefile
sbin/devd/tests/client_test.c
Add ATF test cases for reading events from both devd socket types.

r266519:
sbin/devd/devd.8
sbin/devd/devd.cc
Create a new socket, of type SOCK_SEQPACKET, for communicating with
clients. SOCK_SEQPACKET sockets preserve record boundaries,
simplying code in the client. The old SOCK_STREAM socket is retained
for backwards-compatibility with existing clients.

r269993:
sbin/devd/devd.8
Fix grammar bug.

r270019 (from bz)
Remove bogus ; at the end of the if condition in order to unbreak gcc builds
after r270004.

MFC after: 4 days
X-MFX with: r270004

Convert devd's client socket to type SOCK_SEQPACKET.

This change consists of two merges from projects/zfsd/head along with the
addition of an ATF test case for the new functionality.

sbin/devd/tests/Makefile
sbin/devd/tests/client_test.c
Add ATF test cases for reading events from both devd socket types.

r266519:
sbin/devd/devd.8
sbin/devd/devd.cc
Create a new socket, of type SOCK_SEQPACKET, for communicating with
clients. SOCK_SEQPACKET sockets preserve record boundaries,
simplying code in the client. The old SOCK_STREAM socket is retained
for backwards-compatibility with existing clients.

r269993:
sbin/devd/devd.8
Fix grammar bug.

CR: https://reviews.freebsd.org/rS266519
MFC after: 5 days
Sponsored by: Spectra Logic